Turbines are known in the art for extracting energy from a fluid and converting the extracted energy into work. For example, a typical turbine includes alternating stages of stationary nozzles attached to an outer casing and rotating blades attached to a rotor. As a working fluid, such as steam, air, or combustion gases, flows through the turbine, the stationary nozzles redirect and accelerate the working fluid onto the subsequent stage of rotating blades to cause the rotating blades to turn the rotor. A shaft typically couples the rotor to a work piece so that rotation of the rotor turns the work piece. For example, the shaft may couple the rotor to a generator so that rotation of the rotor operates the generator to produce electricity.
The shaft typically extends through a tunnel that is itself located inside an exhaust frame that surrounds the turbine. Occasionally, sections of the shaft must be removed from the turbine to facilitate maintenance and/or repairs to the turbine or associated components. Sections of the shaft are delicately balanced and may weigh anywhere from several hundred to several thousand pounds, or more. In addition, access to the shaft is somewhat restricted by the surrounding tunnel and exhaust frame. As a result, removal and installation of the shaft presents a number of difficulties such as a confined space, pinch points, and awkward manual lifting of the shaft. In addition, no special tools exist to lift, support, and remove the shaft with the exhaust frame installed. As a result, the weight of the shaft implicates safety and health concerns to avoid personnel injuries and/or damage to the shaft or nearby equipment, and the time required to safely move the shaft implicates the duration of the outage associated with the maintenance and/or repairs.
Various systems and methods have been used to support the shaft during installation and removal of the shaft from the turbine. For example, the shaft may be manually supported by a sufficient number of workers until the shaft is clear of the exhaust frame and can be supported by chain falls and/or a crane. Although this method is relatively expedient, it may create unacceptable health or safety risks to the workers, may require partial or complete removal of the exhaust frame, and may not be possible for heavier shafts. Another technique is to construct a temporary track in the tunnel or exhaust frame to support the shaft. Although the track reduces the health and safety risks, the construction and subsequent removal of the track is itself time consuming and may extend the duration of the outage associated with the maintenance and/or repairs. Therefore, an improved system and method for supporting the shaft during installation and/or removal would be useful.